Semiconductor-based lighting systems and lighting system components for automotive use

ABSTRACT

A modular semiconductor light source assembly includes a semiconductor light source, such as a light emitting diode, which is mounted on a substrate which supplies electricity to the light source and which assists in removing waste heat therefrom. Substantially all of the light emitted by the LED is transferred to a lens by a light pipe, the cross section of the light pipe increasing from the light source to the lens and the lens having a general D-shape such that the light pattern formed by the lens is constrained in a first direction orthogonal to a second direction. The assembly can be combined with other similar assemblies or other light sources in a light fixture to produce a desired overall beam pattern such as a automobile headlamp low beam or high beam pattern.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No.60/740,125, filed Nov. 28, 2005.

This application is a divisional application and continuation of U.S.patent application Ser. No. 11/393,023, filed Mar. 30, 2006, now U.S.Pat. No. 7,560,742. The disclosure of the above application isincorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates to lighting sources for automotivelighting. More specifically, the present invention relates tosemiconductor-based lighting systems and lighting system components foruse in automotive lighting systems.

BACKGROUND OF THE INVENTION

With recent advances in semiconductor light sources, such as high outputwhite light emitting diodes (LEDs), interest has developed in employinglight elements which utilize semiconductor light sources to constructautomotive lighting systems such as headlamps, warning lamps, fog lampsand signaling lamps. Such semiconductor light elements can offer avariety of advantages over conventional incandescent and gas dischargelight sources, including much smaller required volumes for the lightelements with semiconductor sources, resulting in a wider range ofpossible designs and styling, as well as potentially increased longevityand reliability.

However, light elements employing semiconductor sources also suffer fromdisadvantages, including lower light output levels than comparableincandescent and/or gas discharge light sources and a sensitivity toover-heating of the semiconductor light source which can result infailure of the semiconductor light sources.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a novelsemiconductor light source assembly which obviates or mitigates at leastone disadvantage of the prior art.

According to a first aspect of the present invention, there is provideda modular semiconductor light source assembly comprising: a substrate; asemiconductor light source mounted to the substrate, the substrateproviding electrical power to the semiconductor light source andremoving waste heat generated by the semiconductor light source; a heatsink in thermal communication with the substrate to remove waste heattherefrom; a light pipe having a first end adjacent the semiconductorlight source, to capture substantially all of the light emitted from thesemiconductor light source, and a second end; and a lens having ageneral D-shape, the second end of the light pipe engaging the lens suchthat the light from the emitted by the semiconductor light source isemitted from the lens in a pattern wherein the emitted light is spreadin a first direction and is constrained in a second direction, thesecond direction being orthogonal to the first.

Preferably, the semiconductor light source is a light emitting diode.

The present invention provides a modular semiconductor light sourceassembly which includes a semiconductor light source, such as a lightemitting diode, which is mounted on a substrate which supplieselectricity to the light source and which assists in removing waste heattherefrom. Substantially all of the light emitted by the LED istransferred to a lens by a light pipe, the cross section of the lightpipe increasing from the light source to the lens and the lens having ageneral D-shape such that the light pattern formed by the lens isconstrained in a first direction orthogonal to a second direction. Theassembly can be combined with other similar assemblies or other lightsources in a light fixture to produce a desired overall beam patternsuch as a automobile headlamp low beam or high beam pattern or a foglamp or driving lamp pattern.

BRIEF DESCRIPTION OF THE DRAWINGS

Preferred embodiments of the present invention will now be described, byway of example only, with reference to the attached Figures, wherein:

FIG. 1 shows a side view of a modular semiconductor light sourceassembly in accordance with the present invention;

FIG. 2 shows a ray diagram illustrating the refraction of light througha light pipe and lens of the assembly of FIG. 1;

FIG. 3 shows a resulting beam pattern produced by light emitted from thelens of the assembly of FIG. 1;

FIG. 4 shows a side view of another embodiment of a modularsemiconductor light source assembly in accordance with the presentinvention;

FIG. 5 shows a ray diagram illustrating the refraction of light througha light pipe and lens of the assembly of FIG. 4;

FIG. 6 shows a resulting beam pattern produced by light emitted from thelens of the assembly of FIG. 4;

FIG. 7 shows a side view of yet another embodiment of a modularsemiconductor light source assembly in accordance with the presentinvention;

FIG. 8 shows another embodiment of a lens and light pipe for use with amodular semiconductor light source assembly in accordance with thepresent invention;

FIG. 9 shows another embodiment of a modular semiconductor light sourceassembly in accordance with the present invention;

FIG. 10 shows an automotive headlamp fixture constructed with modularsemiconductor light source assemblies in accordance with the presentinvention;

FIG. 11 shows an automotive driving or fog lamp fixture constructed withmodular semiconductor light source assemblies in accordance with thepresent invention; and

FIG. 12 shows an exploded view of the driving or fog lamp fixture ofFIG. 11.

DETAILED DESCRIPTION OF THE INVENTION

As described above, light elements constructed with semiconductor lightsources suffer from disadvantages in that the amount of light emitted bysemiconductor light sources, such as light emitting diodes (LEDs) isgenerally less than the light emitted by incandescent or gas dischargelight sources. Further, semiconductor light sources are sensitive toover-heating conditions and operation of the semiconductor light sourcewith excessive semiconductor junction temperatures will decrease theexpected operating lifetime of the semiconductor light source.

Accordingly, the present inventors have determined that semiconductorlighting systems must include optics which are carefully designed toefficiently form desired beam patterns with the light emitted by thesemiconductor light source. Further, the semiconductor lighting systemsmust allow for sufficient cooling of the semiconductor light sourcetherein to prevent the semiconductor junction temperature from exceedingthe acceptable operating temperature range during normal operatingconditions.

At the same time, the present inventors have also determined thatautomotive lighting systems employing semiconductor light sources areparticularly suited to construction from modular light sourcecomponents.

In FIG. 1 a modular semiconductor light source assembly in accordancewith the present invention is indicated generally at 20. Light sourceassembly 20 comprises a semiconductor light source, such as lightemitting diode (LED) 24, which is mounted to a substrate 28. Substrate28 can be any suitable substrate on which LED 24 can be mounted, butpreferably substrate 28 is a printed circuit board which provideselectrical connections to LED 24 and which assists in transferring wasteheat from LED 24. For example, substrate 28 can be an epoxy orphenolic-based member which includes electrically conductive traces onits surface and which includes a layer of heat transfer material, suchas aluminum or copper. A heat sink 32 is attached to substrate 28 toaccept heat waste heat from LED 24 via substrate 28. Heat sink 32 can beformed from aluminum or any other suitable heat transfer material aswill occur to those of skill in the art. It is contemplated that, if itis desired to employ two or more of assemblies 20 in a light fixture, asdescribed below, then heat sink 32 and/or substrate 28 can be common toeach assembly 20.

The light which is emitted by LED 24 at its surface opposite substrate28 is captured by a light pipe 36 which abuts the emitting surface ofLED 24 to capture substantially all of the light emitted by LED 24.Light pipe 36 can be a fiber optic cable, a light guide manufacturedfrom polycarbonate or transparent silicone rubber or moldable acrylicresins, such as Acrymid™ 815, sold by CYRO Industries of Rockaway, N.J.,or any other suitable method of transferring light from a light sourceto a desired location.

To ensure the capture of substantially all of the light emitted by LED24, the diameter of light pipe 36 preferably tapers from its smallestcross section, adjacent LED 24 where it is preferably at least as largeas the light emitting surface of LED 24, to a larger cross section wherelight pipe 36 contacts a lens 40. Lens 40 can be fabricated of anysuitable material, such as polycarbonate, silicone rubber or moldableacrylic resins, such as Acrymid™ 815, provided only that the selectedmaterial preferably has an index of refraction which is equal to orgreater than the index of refraction of light pipe 36.

Light pipe 36 is optically connected to lens 40 such that substantiallyall of the light emitted by LED 24 is transferred to lens 40. If lightpipe 36 is fabricated from the same material as lens 40, such as if bothare acrylic, then light pipe 40 can be optically connected to the lensby fusing light pipe 36 to lens 40. If light pipe 36 and lens 40 aredissimilar materials, such as transparent silicone rubber and acrylicrespectively, then light pipe 36 can be optically connected to lens 40by abutting it against lens 40 and applying a suitable adhesive or byany other suitable manner as would occur to those of skill in the art.

In the present invention, it is presently preferred that light pipe 36and lens 40 be manufactured as a single component, for example bymolding them from acrylic, to avoid tolerancing difficulties which mayotherwise occur in aligning the optical interfaces/connections betweenlight pipe 36 and lens 40.

Many automotive lighting systems require the production of specificlight patterns, such as headlamp beam patterns, driving lamp patterns orfog lamp patterns with specific shapes and characteristics which aredetermined by regulation or need. In particular, many automotivelighting needs require beam patterns wherein the emitted light is spreadhorizontally but constrained vertically. Accordingly, in the embodimentof FIG. 1, lens 40 is preferably generally D-shaped in cross sectionsuch that light entering lens 40 from light pipe 36 is constrainedvertically and spread horizontally, relative to the orientation of lens40 in FIG. 1, as best seen in FIGS. 2 and 3.

FIG. 4 shows another embodiment of a modular semiconductor light sourceassembly 100 in accordance with the present invention wherein componentswhich are similar to those of the embodiment of FIG. 1 are indicatedwith like reference numerals. As shown, in this embodiment LED 24 islocated on substrate 28 offset from the vertical centerline 44 of lens40. While light pipe 36 still transfers substantially all of the lightemitted by LED 24 to lens 40, the offset (or tilt) of the centerline oflight pipe 36 with respect to the centerline of lens 40 results in themodified beam pattern illustrated in FIGS. 5 and 6. As can be seen, byoffsetting LED 24 below the centerline of lens 40, the resulting beampattern of light emitted from lens 40 is further constrained vertically.

As will now be apparent to those of skill in the art, LED 24 and lightpipe 36 can be positioned in a variety of locations with respect tovertical centerline 44 to alter the vertical constraint of the beampattern produced by modular semiconductor light source assembly 100.

FIG. 7 shows yet another embodiment of a modular semiconductor lightsource assembly 200 in accordance with the present invention whereincomponents which are similar to those of the embodiments of FIGS. 1 and4 are indicated with like reference numerals. As shown in thisembodiment, substrate 28 includes two LEDs 24 a, 24 b mounted on it,each with a respective light pipe 36 a, 36 b to transfer the lightproduced by the respective LED 24 a, 24 b to lens 40. By positioningLEDs 24 a and 24 b appropriately on substrate 28, one or both of lightpipes 36 a and 36 b can be offset with respect to vertical centerline44. Thus assembly 200 can produce beam patterns from the combinedoutputs of LEDs 24 a and 24 b and larger patterns can be formed orpatterns can be formed with relative “hotspots” wherein the light fromLEDs 24 a and 24 b overlap in the pattern.

FIG. 8 shows another embodiment of a lens 220 for use with assemblies20, 100 and/or 200. As illustrated, lens 220 is generally cruciform incross section, comprising a pair of orthogonally oriented D-shapedmembers, each similar to lens 40. Lens 220 thus can create a beampattern which is constrained both horizontally and vertically. If thecenterline of light pipe 224, which transfers light emitted by LED 24 islocated at the centerline of each of the D-shaped members, then theresulting beam pattern is generally square. However, other shaped beampatterns can easily be obtained by moving the centerline position oflight pipe 224 with respect to the centerline of each of the D-shapedmembers forming lens 220.

FIG. 9 shows another embodiment of a modular semiconductor light sourceassembly 250 which, as can be seen, is similar to modular semiconductorlight source assembly 20 and wherein similar components are indicatedwith like reference numerals to those utilized in FIG. 1. As shown, inassembly 250 the “D” shape of lens 254 has been somewhat distorted withrespect to the regular elliptical shape (shown in dashed line) of lens40 of assembly 20. Specifically, lens 254 has been extended forward atits lower edge and withdrawn at its upper edge with respect to theregular elliptical shape (shown in dashed line) of lens 40 of assembly20. Such a non-elliptical shape will vertically constrain the lightemitted by assembly 250 such that more light is emitted from the lowerportion of lens 254 than the upper portion of lens 254. Assembly 250, orsimilar non-elliptical assemblies, can be preferred for use inconstructing light fixtures such as fog lamps or driving lamps whereinit is preferred or required that the resulting light pattern provide alarger proportion of the light in the lower part of the light pattern.Further, assembly 250 can employ an offset light pipe 36 to furtherdirect the light emitting form assembly 250.

While not illustrated, it should be apparent to those of skill in theart that lens 254 can have a wide range of non-elliptical shapes toachieved desired light emission patterns. Further, lens 254 need not beregularly shaped and can include, for example, one or more facets in thenon-elliptical shape, such facets providing areas of reduced light inthe resulting light pattern. A variety of other shapes of lens 254 andor patterns of facets or other light focusing structures for lens 254can be employed as will occur to those of skill in the art and the terms“generally D-shaped” or “general D-shape” used herein are intended tocomprise all such shapes.

As should now be apparent, desired beam patterns can advantageously beformed with combinations of the above-described modular light sourceassemblies and/or other light sources.

FIG. 10 shows a headlamp fixture 300 which has been constructed from acombination of assemblies 20, 100, 200 and/or 250 and a projector device304, such as that described in co-pending U.S. application Ser. No.11/290,853 filed on Nov. 30, 2005 and assigned to the assignee of thepresent invention. Projector device 304 provides areas of high intensitylight for the desired beam pattern while modular semiconductor lightsource assemblies 20, 100, 200 or 250 provide spread light for thedesired beam pattern. As mentioned above, when multiple assemblies 20,100, 200 and/or 250 are employed in a fixture, such as headlamp fixture300, two or more assemblies 20, 100, 200 and/or 250 can share a commonheat sink. In the illustrated fixture 300, two of assemblies 20, 100,200 and/or 250 of the bottom tier and four of the assemblies 20, 100,200 and/or 250 of the top tier share heat sink 32 a, while the remainingthree of assemblies 20, 100, 200 and/or 250 of the bottom tier and threeof the assemblies 20, 100, 200 and/or 250 of the top tier share heatsink 32 b.

Some of assemblies 20, 100, 200 or 250 can be employed to provide filllight for desired beam patterns while projector device 304 can provideany necessary hotspots for those beam patterns. For example, the bottomfive assemblies 20, 100, 200 or 250 can be used for producing fill lightfor a low beam headlamp pattern while the top seven assemblies 20, 100,200 or 250 can be used for producing fill light for a high beam headlamppattern. Alternatively, or in addition, one or more of assemblies 20,100, 200 or 250 can be illuminated when the steering wheels of thevehicle are turned to provide steering light to illuminate the road inthe direction the vehicle will travel.

As will be apparent from FIG. 10, the thickness of lens 40 or 254 inassemblies 20, 100, 200 and/or 250 can be varied to alter the horizontalspread of the beam pattern produced by assemblies 20, 100, 200 and/or250. In fixture 300, some of assemblies 20, 100, 200 and/or 250 haverelatively thick lenses 40 or 254, while others have relatively thinlenses 40 or 254 to obtain the desired beam pattern.

In addition to headlamp fixtures, it is contemplated that a variety ofother automotive lighting systems can be constructed with modularsemiconductor light source assemblies in accordance with the presentinvention, including taillight fixtures and/or daytime running lightfixtures. For example, FIGS. 11 and 12 show a lighting fixture 400 whichcan be used as a Fog Lamp or Driving Lamp. As illustrated, fixture 400includes five modular semiconductor light source assemblies 20, 100, 200or 250 which can be each of one type, e.g.—five instances of modularsemiconductor light source assembly 20, or which can include two or moredifferent types of modular light source assemblies, e.g.—one of modularsemiconductor light source assembly 20, three modular semiconductorlight source assemblies 100 and two modular semiconductor light sourceassemblies 200 to produce a desired emitted beam pattern from fixture400.

Each of the modular semiconductor light source assemblies 20, 100, 200or 250 are mounted through a bezel 404 which is in turn mounted within afixture body 408 and enclosed by a clear lens 412. While in theillustrated embodiment the lenses of each modular semiconductor lightsource assembly 20, 100, 200 or 250 are mounted substantially parallelto each other it is contemplated that one or more of the modularsemiconductor light source assemblies can be mounted in fixture 400 withtheir respective lenses angled horizontally to spread or “wrap” the beampattern produced to the front and side of the motor vehicle, etc. asrequired for the particular desired beam pattern.

As will be apparent from FIGS. 10 and 11, the use of modularsemiconductor light source assemblies 20, 100, 200 or 250 permit avariety of stylistic light fixtures to be created, as desired.

The present invention provide a modular semiconductor light sourceassembly which includes a semiconductor light source, such as a lightemitting diode, which is mounted on a substrate which supplieselectricity to the light source and which assists in removing waste heattherefrom. Substantially all of the light emitted by the LED istransferred to a lens by a light pipe, the cross section of the lightpipe increasing from the light source to the lens and the lens having ageneral D-shape such that the light pattern formed by the lens isconstrained in a first direction orthogonal to a second direction. Theassembly can be combined with other similar assemblies or other lightsources in a light fixture to produce a desired overall beam patternsuch as an automobile headlamp low beam or high beam pattern.

The above-described embodiments of the invention are intended to beexamples of the present invention and alterations and modifications maybe effected thereto, by those of skill in the art, without departingfrom the scope of the invention which is defined solely by the claimsappended hereto.

1. A headlamp fixture, comprising: one or more modular semiconductorlight source assemblies for producing a spread portion of a desired beampattern, wherein the one or more modular semiconductor light sourceassemblies are positioned such that each lens of the one or more modularsemiconductor light source assemblies is angled horizontally to spreadthe light of said spread portion of said desired beam pattern todifferent areas surrounding a vehicle; a projector light source,operably associated with the one or more modular semiconductor lightsource assemblies for producing a high-intensity portion of said desiredbeam pattern; and each of said one or more modular semiconductor lightsources including a lens having a general D-shape used in conjunctionwith a light pipe having a first end and a second end, the second end ofthe light pipe engaging the lens such that the light emitted by said oneor more modular semiconductor light sources is emitted from the lens ina pattern wherein the emitted light is spread in a first direction andis constrained in a second direction, the second direction beingorthogonal to the first.
 2. The headlamp fixture of claim 1, wherein theone or more modular semiconductor light source assemblies are employedto provide fill light for said beam pattern, and the projector lightsource can provide hotspots for said beam pattern.
 3. The headlampfixture of claim 2, wherein the one or more modular semiconductor lightsource assemblies are used to provide light to illuminate a road in thedirection a vehicle will travel.
 4. The headlamp fixture of claim 1,wherein the one or more modular semiconductor light source assembliesare used as one selected from a group comprising: a taillight fixturefor a vehicle, a daytime running light for a vehicle, a fog lamp or adriving lamp.
 5. The headlamp fixture of claim 1, wherein said one ormore modular semiconductor light source assemblies further comprising: asubstrate upon which the semiconductor light source is mounted; a heatsink in thermal communication with the substrate to remove waste heattherefrom; wherein the first end of the light pipe is used to capturesubstantially all of the light emitted from the semiconductor lightsource.
 6. The headlamp fixture of claim 5, wherein the lens of each ofthe one or more modular semiconductor light source assemblies is maderelatively thicker and used in combination with the lens of each of theone or more modular semiconductor light source assemblies which is maderelatively thinner to produce a desired beam pattern.
 7. The headlampfixture of claim 1, wherein the thickness of the lens can be varied toalter the horizontal spread of the beam patterns produced by the one ormore modular semiconductor light source assemblies.